1. Field of the Invention
The invention relates to supported cobalt catalysts used in Fischer Tropsch hydrocarbon synthesis. More specifically, the invention is directed to titania supported cobalt catalysts and their stabilization.
2. Background of the Disclosure
Coprecipitated titania supports are described in "Benzene Hydrogenation Over Ni/TiO2-ZrO2 Catalyst," Ikai Wang, et al., Appl. Cat., Vol. 18, p. 273-283, (1985) and "Dehydrogenation of Ethylbenzene and Ethylcyclohexane Over Mixed Ternary Oxide Catalyst Containing TiO2-ZrO2, " Jung-Chung Wu et al., Appl. Cat., Vol. 18, p. 295-310, (1985). In the former reference, nickel oxide is placed on mixed titania-zirconia oxides, binary oxides, which are then calcined at 90.degree.-500.degree. C. and reduced at 300.degree. C. to form a dehydrogenation catalyst. None of the catalysts are subjected to high temperature oxidative regeneration nor used in a Fischer-Tropsch synthesis reaction. In the latter reference, three component mixed oxides containing titania and zirconia as two of the components, were tested as dehydrogenation catalysts. These catalysts, which did not contain metal, were examined by x-ray diffraction following calcination at 650.degree. C. The authors indicate that most of the catalysts showed the presence of TiO2 rutile at this temperature; not a stabilized anatase phase. Ternary metal oxides are represented by the general formula A.sub.x B.sub.y O.sub.z and are distinguishable from three component metal oxides which have a formula of AO.sub.x BO.sub.y CO.sub.z.
Consequently, the prior art does not provide for cobalt containing catalysts that can be calcined on a titania-containing support to high temperature (up to 750.degree. C.) in which the surface area of the support is maintained and the anatase to rutile transformation prevented, in turn preventing the cobalt from reacting with the support to form cobalt titanate, thereby helping maintain a high dispersion of cobalt following a low temperature rereduction.